In the modern world, computing devices are getting smaller, more powerful, and cheaper to produce. These small mobile devices require text input devices that are not quite as cumbersome as keyboards. Miniature keyboards and soft keyboards are available on small handheld devices, such as personal digital assistants (PDAs), but are only practical for small data entry operations. Further, current techniques adopted by many telecommunication companies overload each key of a typical phone keypad with as many as 4-6 symbols, which requires cycling through the range of symbols to enter a single vowel, consonant, and/or a modifier. In general, such keyboards use up valuable real estate on these devices and are difficult to use. Users who are less-literate and not computer proficient generally find the conventional keyboards to be the most intimidating parts of these computing devices.
Conventional ways for inputting phonetic scripts, such as Indic, Sinhalese, Burmese, Thai, Vietnamese, and the like typically include one or more of the following techniques:
First, as described above data entry into computers is performed using keyboards. The complexity and size of keyboards depend on the number and type of characters present in a script. Typically, phonetic scripts tend to have large and/or complex character sets. Such scripts can present great difficulties in the design as well as use of these keyboards. For example, Indic scripts have nearly 30 to 40 consonants, 12 to 15 vowels, and about 12 to 15 phonetic modifiers and half consonant modifiers. As a result, the current techniques employ either overlays on a QWERTY keyboard, such as Inscript where several key strokes may be required to enter a desired syllable. The keyboard approach provides incomplete visibility of the entire character map at any given point of time. In addition, these keyboards are non-intuitive and can require extensive practice period for proficiency. Further, character entries using such keyboards tend to be very slow. Furthermore, the increasing demand for smaller and smaller devices, such as PDAs and mobile phones is driving keyboard designs toward a smaller keypad, making it impractical to use keyboards accommodating such large character sets.
Second, a technique called Simpli is based on a soft keypad activated using a stylus. Phonetically related characters (consonants/modifiers) are grouped into layers and become dynamically available when the group-leader character is accessed or touched. However, this technique requires the user to first recollect the group of the desired character and further requires recollecting the leader of the group. Third, the Gesture Keyboard facilitates in resolving the above problems, but requires peripheral devices and considerably large display or digitizer real estate to display all of the base consonants and vowels.
There are other input techniques for scripts, such as Roman. However, these techniques work when the number of symbols is small, and do not leverage the syllabic structure of Indic scripts. There are many other conventional techniques for Oriental scripts, such as Japanese, Chinese, and the like. However, these scripts have significantly large number of symbols and do not have any syllabic structure. Therefore, these techniques do not reflect or leverage the mental models of a user of syllabic scripts.
There are also many handwriting inputting techniques as an alternative input technique for scripts, such as Roman and Oriental, and are available on PDAs and mobile phones. However, the corresponding recognition technology is in its infancy for applying them to Indic scripts. These techniques are not yet reliable enough to support unconstrained handwriting input of hundreds of syllabic characters that are present in scripts, such as Indic scripts.